Mechanical fuze operable on grazing impact



Aug. 9, 1966 T. L. LIBBY ET AL MECHANICAL FUZE OPERABLE ON GRAZING IMPACT Flled May 11, 1964 2 Sheets-Sheet l 29 28 30 A 2 \K\\\\\\\\\\\\\\\\\\\\\\% |4- I7 I5 44 INVENTORS.

TERRY L. LIBBY BY GEKjGE WE/BQZM q/tmim w. 7 ATTORNEYS.

Aug. 9, 1966 UBBY ET AL 3,264,995

MECHANICAL FUZE OPERABLE ON GRAZING IMPACT Flled May 11, 1964 2 Sheets-Shee1; 2

INVENTORS. TERRY L. Ll BBY GEORGE WE Yaw ATTORNEYS.

United States The present invention relates to fuzes, and it provides improved mechanical means for arming missiles and firing them on contact. The invention is of general utility for use with missiles rotated in flight.

The principal object of the present invention is to provide, in combination with firing means, a gyroscopic element which functions in such a way as to assure that the projectile will fire on impact with a target even at such low angles of incidence as characterize grazing strikes.

Another object of the invention is to provide this as sured firing means in combination with improved arming means.

For a better understanding of the invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following description of the appended drawings in which there is shown a preferred embodiment of fuze structure in accordance with the invention.

-In the drawings:

FIG. 1 is an elevational sectional view through a fuze structure in accordance with the invention;

FIG. 2 is a top view of the improved fuze, with the ogive removed and a portion of the striker broken away for clarity in exposition;

FIG. 3 is a cross sectional view through the fuze body member; and

FIG. 4 is a top plan view of the fuze body member showing the slider and associated elements in safe position.

Referring now specifically to FIGS. 1 and 2, attention is first directed to a metallic slider element 10. The slider element carries and positions a primary explosive or primer L1. This primary element is shown in safe position in all of the figures of the drawings. The discussion of the firing elements of the fuze is prefaced by the statement that the structure is armed by the slider which moves in such fashion as to align the primary explosive 1 1 with a firing pin 9. Discussion of the manner in which this occurs is deferred until after the firing means is described, although it will of course be understood that, like all fuzes, the fuze in accordance with the present invention is armed before it is fired.

The mounting structure for the fuze is provided by a body member 12 which is formed generally in the shape of a double-ended cap having a rearwardly extending screw-threaded portion 13 and a forwardly extending portion 14, these two portions being separated by a partition 15 as shown in FIG. 3. The screw-threaded portion 13 is secured to the body of the rocket warhead (not shown). The partition 15 is formed with a central aperture 16 to provide continuous communication for the firing train or lead which extends from the primer 11 (when in armed position) to the principal explosive charge (not shown) which is contained within the warhead body. The fuze body member is preferably made of a suitable aluminum alloy material. Portion 14 is formed with a depression or track 17 in which the slider 10 linearly moves, and also with smaller transversely extending tracks 18 and 19 in which the weights 20 and 21 move, against the force of springs 22 and 23, respectively. The sides of track 17, near its radially outer end, are formed with locking surfaces 24 and 25, for a purpose presently described.

The description, having covered the body member 12,

' atent the slider 10, the primary explosive 11, and briefly touched on some of the arming elements in portion 14, now returns to the elements related to firing of the fuze.

As best shown in FIG. 1, the cap portion 14 is closed by a fuze plate 26 which is formed with an upwardly extending boss .27 and an outer annular flange 28 and is preferably made of an aluminum alloy material. The fuze plate 26 is suitably secured to the fuze body 12 as by crimping. Projecting through the central boss 27 is the firing pin 9 which is formed with a pin portion and a head portion 29 and is preferably made of an aluminum alloy. Between the head portion 29 and the plate 26 is disposed a spring 30. Secured to the head of the firing pin are a plurality of angularly symmetrically displaced radially and forwardly extending springs 33, 34, 35, and 36, each made of spring steel and carrying a steel weight, the weight being respectively numbered 37, 38, 39, and 40 the springs 33-36 and the weights 37-40 constituting a centrifugal governor.

Secured to portion 14 of the body is a conventional ogive 41 against the fore portion of which bears a striker member 42. The cup-shaped striker member bears against the weights in such manner as slightly to compress the spring 30.

Particular attention is directed to the gyroscopic inertia ring 43 disposed within annular flange 28. Attention having been directed to this element, the description now proceeds to a discussion of assembly, and thereafter overall operation will again be discussed.

In assembly, the elements shown in FIGS. 3 and 4 are first put together and the fuze plate 26 is set in place, together with inertia ring 43. Then the firing pin mechanism carrying the four weighted initiating springs 33-36 is set in place with the arming spring 30 in compression. The cupped striker 42 is attached to ogive 41, which is set on the steel weights 37-44) such that the assembly further compresses the arming spring 30 and sinks the firing pin 9 further toward the rear. The assembly locks the slider group in the safe or unarmed position. This slider group is unbalanced in mass such that section A to the left of the firing pin is heavier than section B to the right. This unbalance moves the slider to the left (FIG. 1) once centrifugal force has removed the lock plungers 20 and 21 in the delayed operation, provided the firing pin is cleared at 44. Then the primer 11 is locked under the firing pin 9.

The centrifugal force, due to the projectile spin and operating to delay arm the fuze, also spins the free inertia ring 43 and the double-butterfly initiating springs 33-36, weighted by weights 137-40. That force tends to straighten out the butterfly which is under spring compression by the arming spring. Such movement when sufiiciently progressed clears the firing pin at 44 (i.e., moves its point in front of the level of the primer carriage). This pin 9 remains free so long as the threshold spin rate is exceeded. The initiating spring bias is made strong enough to drive the firing pin 9 into the primer 11 when the spin rate falls appreciably below the threshold. Such condition is unlikely in tactical missions.

A head-on collision will crush the relatively thin ogive 41, drive the striker 42 against the initiating springs 33-36 and the firing pin 9 into the primer 11, and detonate the high explosive.

But suppose target contact occurs as a grazing strike, for example, at about 5. Then the ogive 41 might not be deformed sufficiently to depress the striker. Here another aspect of the invention goes into action. The projectile is in rotation at many revolutions per second; the initiating spring 33-36 is deflected essentially with the line of flight; it rests on the whirling inertia ring 43 and against the striker 42. The relatively light graze contact occurs with a corresponding change in the direction of flight. A component of the force imparted to the projectile by the target tends to tilt or tip the axis of the pin 9 and the whirling elements 33-40. But the rotating mass 43 is a gyroscope, with a large moment of inertia and stability of plane. The gyroscope 43 does not tilt and forces one or more of the four weighted blades against the striker 42, and the fulcrum action drives the firing pin 9 into the primer 11.

The tilt is essentially instantaneous as are the associated reactions such that detonation occurs effectively on target.

The inertia member 43 rotates at the same rate of speed as the fuze plate 26. This can be assured by loosely coupling the inertia member and the plate together as by annularly spaced pins, for example, projecting loosely into registering depressions in the thick annular portion of the inertia member 43.

The arming spring 30 is desirable in rocket-propelled projectiles to aid removal of the firing pin under set back forces. It is not required in other types of projectiles.

This slider 10 arrangement provides a simple means of giving a safe arming distance to ammunition which uses rocket boost in conjunction with spin jets. Once the fuze arms, the mechanism locks the out-of-line element 11 in the armed position. The fuze can be used on those projectiles which require a boost in spin rate to maintain dynamic stability.

In addition to the safe arming distance feature, the arming arrangement will not allow the fuze to arm in case of motor failure since arming takes place at a spin rate greater than that at the muzzle of the gun.

Slider 10 provides the out-of-line safety feature since the primary explosive, detonator or primer, illustrated by 11, is held in the safe or armed position by the slider. The slider is held in the safe position by spring-loaded weights 20 and 21. The slider is formed to retain balls 46 and 47 which lock the slider in the armed position after arming. The balls 46 and 47 are pressed outwardly by centrifugal force.

The operation of the arming device is as follows: Weights 2021 and springs 22-23 are designed to release slider 10 at a spin rate which is indicative of the desired arming distance. When the spin rate has increased to the point where the centrifugal force acting on the weights overcomes the preload of the springs, the slider will move the primary explosive to the in-line or armed position (with 11 under and in line with 9 since its center of gravity is near the balls. With the slider in the armed position, the two balls are forced into detents 24 and 25 in the housing by force components. It will be noted that the weights slide on pins 50 and 51.

This invention provides improved safety in addition to improved contact detonation. The sliding primer carrier 10 is double locked with spring loaded, weighted latches 20 and 21 such that it can be moved to armed position only by centrifugal forces of a predetermined magnitude applied simultaneously to both latches. Then while the latches are withdrawn, a centrifugal force must be applied to drive the primer carrier 10 and primer 11 into the armed position. Now, there is a further safety in the key or latch provided by the spring-loaded firing pin 9 acting at right angles so that it must clear at 44 to permit the slider to move. Arming action can be initiated in the assembled fuze only by activating the three latches such that all are free of the slider.

The inertia ring 43 is supported by the fuze plate. But the ring is free to move within a limited volume as indicated in FIG. 1. A relative movement towards the front applies a force on the weighted initiating spring. And

Such

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a fuze for a spinning projectile, the combination of:

a firing pin for detonating the projectile;

a gyroscopic inertia ring;

actuating means for driving said firing pin into firing position, said actuating means including at least one element normally oriented to be spaced from said ring;

said inertia ring maintaining stability of plane, whereby impact forces cause said element to strike said inertia ring and .to drive the firing pin into firing position;

the inertia ring being mounted to spin relative to the longitudinal axis of the projectile;

and a mounting for the firing pin, which mounting permits the firing pin to be displaced rearwardly into firing position or advanced forwardly into a safe position;

the actuating means comprising a plurality of radially extending spring elements having their inner ends secured to the pin.

2. The combination in accordance with claim 1 in which the spring elements are weighted.

3. The combination in accordance with claim 2, and further having an ogival cap for the projectile and a rearwardly extending striker extending from the inner front of the ogive into a spanning relationship with all of said spring elements, so that direct impact of the projectile causes the striker to drive the spring elements rearwardly to drive the firing pin into firing position.

4. The combination in accordance with claim 3 in which the rearwardly extending face of the striker is annular and is located inwardly of the inertia ring and outwardly of the firing pin so that it functions as a fulcrum.

5. The combination in accordance with claim 4 in which the firing pin is biased toward non-firing position by a compression spring.

6. In a fuze for a spinning projectile, the combination of:

a firing pin for detonating the projectile;

a mounting for the firing pin, said mounting being formed to permit the firing pin to be displaced rearwardly into firing position or advanced forwardly into a safe position;

a gyroscopic inertia ring;

actuating means for displacing said firing pin, said actuating means including weighted arms diverging radially outwardly and forwardly from said firing pin and constituting a centrifugal governor, the arms being normally oriented to be spaced from said ring;

and a striker element providing a fulcrum against which said arms are adapted to function as levers to displace said pin into firing position;

said inc-.ntia ring maintaining stability of plane, whereby impact forces cause at least one of said arms to strike said inertia ring and to drive the firing pin into firing position.

7. The combination in accordance with claim 6 in which the actuating means responds to a predetermined rate of spin to displace the firing pin forwardly,

and a slider formed to be unbalanced and, on the application of centrifugal force, to align a primary explosive with the firing pin on condition that the firing pin is displaced sufficiently forward to clear 6 References Cited by the Examiner UNITED STATES PATENTS 2,322,543 6/1943 Patchett l0279 5 2,427,671 9/1947 Graumann et al. 10279 2,462,062 2/ 1949 Beeman 102-79 BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner. 10 G. H. GLANZMAN, Assistant Examiner. 

1. IN A FUZE FOR A SPINNING PROJECTILE, THE COMBINATION OF: A FIRING PIN FOR DETONATING THE PROJECTILE; A GYROSCOPIC INERTIA RING; ACTUATING MEANS FOR DRIVING SAID FIRING PIN INTO FIRING POSITION, SAID ACTUATING MEANS INCLUDING AT LEAST ONE ELEMENT NORMALLY ORIENTED TO BE SPACED FROM SAID RING; SAID INERTIA RING MAINTAINING STABILITY OF PLANE, WHEREBY IMPACT FORCES CAUSE SAID ELEMENT TO STRIKE SAID INERTIA RING AND TO DRIVE THE FIRING PIN INTO FIRING POSITION; THE INERTIA RING BEING MOUNTED TO SPIN RELATIVE TO THE LONGITUDINAL AXIS OF THE PROJECTILE; AND A MOUNTING FOR THE FIRING PIN, WHICH MOUNTING PERMITS THE FIRING PIN TO BE DISPLACED REARWARDLY INTO FIRING POSITION OR ADVANCED FORWARDLY INTO A SAFE POSITION; THE ACTUATING MEANS COMPRISING A PLURALITY OF RADIALLY EXTENDING SPRING ELEMENTS HAVING THEIR INNER ENDS SECURED TO THE PIN. 